Potential use of lasers for penetrating keratoplasty

Abstract

Experimental corneal trephination has been achieved with the 193 nm argon fluoride excimer and 2.9 microns hydrogen fluoride and Er:YAG laser systems. Compared with metal blades and other lasers, the 193 nm excimer laser creates the best quality corneal excision, but has a relatively slow etch rate through the stroma, and its use requires toxic gas. The mid-infrared laser systems trephine the cornea in less than 10 seconds, but cause a 10 microns to 15 microns zone of adjacent stromal damage and create wounds that are approximately 2.5 times larger than wounds made by metal scalpels. The wavelength and laser pulse duration influence the cutting characteristics of the laser. Optical delivery systems using an axicon lens, a rotating slit, and a computer controlled scanning optical system have been developed for penetrating keratoplasty. Selection of the optimal laser system for penetrating keratoplasty must await further experimental studies. Refinements of the laser cavity and delivery system are necessary before clinical studies can begin. A carefully controlled randomized clinical trial comparing laser trephination with conventional mechanical trephines will be necessary to determine the safety and efficacy of a laser trephination system.

Kann die Schnittqualität von Trepanen noch verbessert werden?

“…1989 haben unterschiedliche Arbeitsgruppen wie Lang [21] oder Thompson [22] Abb. 11 Bestimmung der Descemet-(a) und Endothelstauchung (b) am histologischen Präparat: Schnitt durch Schweinecornea mit unbehandelten Einwegtrepanen.…”

Kann die Schnittqualität von Trepanen noch verbessert werden?

“…1989 haben unterschiedliche Arbeitsgruppen wie Lang [21] oder Thompson [22] Abb. 11 Bestimmung der Descemet-(a) und Endothelstauchung (b) am histologischen Präparat: Schnitt durch Schweinecornea mit unbehandelten Einwegtrepanen.…”

Stromal Thermal Effects Induced by Nonmechanical (2.94-µm) Erbium:YAG Laser Corneal Trephination

“…[29][30][31][32] However, higher ablation rates are common undesired effects with Er:YAG laser for this type of intervention 31 but could represent an additional advantage for corneal trephination. 33 The purpose of this study was to perform nonmechanical Er:YAG laser corneal trephinations in corneas of enucleated pig eyes, similar to the technique with the 193-nm excimer laser for PK currently used for all nonvascularized corneal processes in our department. 1,12,34,35 Thermal effects in the corneal stroma and regularity of the trephination edges were assessed with 2 mask materials and different combinations of laser settings.…”

Zum Einsatz eines spezialisierten Excimer-Laser-Systems (ELCS-System) in der Hornhautbank

“…Es werden dadurch zwar langere Bearbeitungszeiten als z. B. beim Axicon-System erreicht, jedoch hat man dadurch ein hohes Maf3 der freien Wahl der Formgebung [30].…”

Kann die Schnittqualität von Trepanen noch verbessert werden?

“…1989 haben unterschiedliche Arbeitsgruppen wie Lang [21] oder Thompson [22] Abb. 11 Bestimmung der Descemet-(a) und Endothelstauchung (b) am histologischen Präparat: Schnitt durch Schweinecornea mit unbehandelten Einwegtrepanen.…”

Stromal Thermal Effects Induced by Nonmechanical (2.94-µm) Erbium:YAG Laser Corneal Trephination

“…[29][30][31][32] However, higher ablation rates are common undesired effects with Er:YAG laser for this type of intervention 31 but could represent an additional advantage for corneal trephination. 33 The purpose of this study was to perform nonmechanical Er:YAG laser corneal trephinations in corneas of enucleated pig eyes, similar to the technique with the 193-nm excimer laser for PK currently used for all nonvascularized corneal processes in our department. 1,12,34,35 Thermal effects in the corneal stroma and regularity of the trephination edges were assessed with 2 mask materials and different combinations of laser settings.…”

Zum Einsatz eines spezialisierten Excimer-Laser-Systems (ELCS-System) in der Hornhautbank

“…Es werden dadurch zwar langere Bearbeitungszeiten als z. B. beim Axicon-System erreicht, jedoch hat man dadurch ein hohes Maf3 der freien Wahl der Formgebung [30].…”

Kann die Schnittqualität von Trepanen noch verbessert werden?

“…1989 haben unterschiedliche Arbeitsgruppen wie Lang [21] oder Thompson [22] Abb. 11 Bestimmung der Descemet-(a) und Endothelstauchung (b) am histologischen Präparat: Schnitt durch Schweinecornea mit unbehandelten Einwegtrepanen.…”

Stromal Thermal Effects Induced by Nonmechanical (2.94-µm) Erbium:YAG Laser Corneal Trephination

“…[29][30][31][32] However, higher ablation rates are common undesired effects with Er:YAG laser for this type of intervention 31 but could represent an additional advantage for corneal trephination. 33 The purpose of this study was to perform nonmechanical Er:YAG laser corneal trephinations in corneas of enucleated pig eyes, similar to the technique with the 193-nm excimer laser for PK currently used for all nonvascularized corneal processes in our department. 1,12,34,35 Thermal effects in the corneal stroma and regularity of the trephination edges were assessed with 2 mask materials and different combinations of laser settings.…”

Zum Einsatz eines spezialisierten Excimer-Laser-Systems (ELCS-System) in der Hornhautbank

“…Es werden dadurch zwar langere Bearbeitungszeiten als z. B. beim Axicon-System erreicht, jedoch hat man dadurch ein hohes Maf3 der freien Wahl der Formgebung [30].…”